1. Field of the Invention
The invention relates generally to a method of forming a contact plug of a semiconductor device and, more particularly, to a method of forming a contact plug of a semiconductor device, wherein void phenomena are present when a subsequent metal layer is formed.
2. Discussion of Related Technology
In general, in fabricating a semiconductor device in one wafer, a plurality of contact holes may be formed and a contact plug is formed in the plurality of contact holes through the same process. For example, a contact plug may be formed in a plurality of contact holes having a different etch area and a different pattern shape while the contact hole has both a line shape and a hall shape like a source line contact hole of a flash memory and a drain contact hole of an isolation type.
FIGS. 1a and 1b are sectional views for illustrating a known method of forming a contact plug of a semiconductor device.
Referring to FIG. 1a, a source/drain junction unit 11 is formed in a semiconductor substrate 10. An interlayer insulation film 12 is formed on the entire surface of the semiconductor substrate 10 including the source/drain junction unit 11. An etch process is then performed to form a contact hole through which a predetermined region of the source/drain junction unit 11 is exposed. Thereafter, the contact hole is filled with a contact plug material 13.
Referring to FIG. 1b, an etch-back process is performed to form a contact plug 13 within the contact hole. The height of the contact plug 13 remaining within the contact hole is varied due to the loading effect, which occurs due to a difference in the etch area and a pattern of the line shape and the hall shape of the contact hole.
Thereafter, a metal layer 14 is formed on the entire surface of the semiconductor substrate 10 including the contact plug 13. At this time, as the height of the contact plug 13 remaining within the contact hole and the line width depending on the level of integration of the device are reduced, the contact size is reduced and a void 15 accordingly is generated within the metal layer 14 upon formation of the metal layer 14. The void 15 causes an electrical defect between the contact plug 13 and the metal layer 14.